In most metalworking operations it is generally advisable to apply fluids to lubricate and cool the metal surfaces at points of frictional contact. Metalworking fluids act, apparently by independent mechanisms, to reduce frictional heat generation by lubrication and to reduce heat build-up by conduction of heat from the surface. The primary benefits of a proper lubricating coolant in metalworking are prolonged tool life and increased speed of operations. Concurrent secondary benefits include a better surface finish and improved dimensional stability of the workpiece.
Hydrocarbon oils, including fatty acids and oils, are known to be good lubricants that reduce friction, and thereby, reduce heat generation in metalworking operations. Lanolin, in particular, is an especially good lubricant for non-ferrous metalworking. However, hydrocarbon oils, by themselves, are not effective coolants. As water has a specific heat twice that of a hydrocarbon oil and will transfer heat two to three times faster than an oil, water is a superior coolant. However, water, by itself, has very little lubricating value. Accordingly, numerous attempts have been made to combine lanolin and water in stable solutions or emulsions for use as lubricating coolants in metalworking operations.
For example, U.S. Pat. No. 2,672,976 to Overath et al., describes a metalworking lubricating consisting of an aqueous emulsion of wool fats and fatty acids saponified with alkali metal hydroxide. This lubricant composition, even as noted by Overath, however, is unsuitable for use with hard water.
In U.S. Pat. No. 4,206,059 to Burton et al., an aqueous emulsion of wool fats, saponified with sodium hydroxide, is proposed as a metalworking lubricant. To achieve a more stable emulsion, Burton describes a cumbersome, multi-step process involving blending melted wool fat with cellulose, circulating the blend with mineral oil under back-pressure through a shearing device, saponification with sodium hydroxide, and then adding sequentially with heat and stirring, ethoxylated alkylphenol, insert filler and finally water. Naturally, such a lengthy and involved process is not very suitable for commercial operations. Further, the lubricant proposed by Burton contains a large amount of mineral oil rendering the lubricant ecologically unattractive.
A mineral oil-free fluid is described in U.S. Pat. No. 4,390,436 to Hernandez. The described water-based metalworking lubricant contains lanolin, a fatty acid amine soap and a thickener in combination with wax. The aqueous metal working fluids of Hernandez, while highly satisfactory in may respects, tend to form a water-insoluble coating on the surface of the workpiece during certain metalworking operations and therefore such compositions generally cannot be continually circulated as a lubricating coolant. Further, it has been found that these compositions can be sensitive to hard water.
Accordingly, it is an object of the present invention to provide novel lanolin emulsions and emulsifiable concentrates for water-based metalworking fluids.
A further object of this invention is to provide hard water-stable lanolin emulsions and emulsifiable concentrates for water-based metalworking lubricating coolants.
Another object of this invention is to provide lanolin emulsions for metalworking fluids that can be readily prepared.
Another object of this invention is to provide a method of cooling and lubricating metal during a metalworking operation.
Another object of this invention is to provide lanolin emulsion concentrates for formulating water-based metalworking fluids.
Yet another object of this invention is to provide a lanolin and water emulsion lubricating coolant for metalworking fluids.
Still another object of this invention is to provide a mineral oil-free lanolin emulsion for metalworking fluids.
Additional objects of the present invention are set forth in, or will be apparent from, the following description of the invention.